The value official for the access tags foot, bicycle and horse indicates a way legally dedicated to specific modes of travel by a law or by the rules of traffic. The tag is to signify the official, binding, legal nature of the dedication. A way may have several official dedications.

In most cases, the official dedication also means that other modes of travel are prohibited. In some countries like Germany such a usage right is also compulsory, travelers must not use a parallel way if an official way is marked. But exclusive or compulsory use is only a deduction based on local laws and traffic rules, it is not the meaning of the tag "official". For compulsory ways use bicycle=designated on the cycleway affected and tag bicycle=use_sidepath on the highway which the cyclist should not use. For pedestrians traffic on footways use sidewalk:foot=designated and foot=use_sidepath on the road.

Do not use official to tag roads reserved for official traffic (police, fire brigade, customs et.al.). Use access=no because these roads are not allowed for the general public.